Using a current workflow step for control of medical data processing

ABSTRACT

Disclosed is a computer-implemented of adapting a biomechanical model of an anatomical body part of a patient to a current status of the patient. The method encompasses determination of a currently executed step of a workflow such as a medical intervention, the result of the determination serving as a basis for adapting and/or updating a biomechanical model of an anatomical body part to the corresponding current status of the patient. The determination of the current workflow step may also be used as basis for controlling an imaging device for tracking entities around the patient or for imaging the anatomical body part or acquiring further data or for urging the user to perform a specific action such as acquisition of information using a tracked instrument such as a pointer. The biomechanical model has been generated from atlas data. The data sets which are generated according to the current workflow step may additionally or alternatively serve as a basis for determining the current workflow step and/or adapting the further workflow.

FIELD OF THE INVENTION

The present invention relates to a computer-implemented method ofadapting a biomechanical model of an anatomical body part of a patientto a current status of the patient, a corresponding computer program, acomputer-readable storage medium storing such a program and a computerexecuting the program, as well as a medical system comprising anelectronic data storage device and the aforementioned computer.

TECHNICAL BACKGROUND

Biomechanical models are used for example to portray changes of anatomywhich might be caused by a medical intervention and to accordinglyupdate patient image data which was used for planning and navigation ofthe intervention. It is also known to conduct such an update on thebasis of spatial sampling data like medical image data generated duringthe intervention.

The present invention has the object of improving use of a digitalbiomechanical model of an anatomical body part.

The present invention can be used for procedures e.g. in connection withmedical navigation systems and image co-registration software likeCranial Navigation and Image Fusion, respectively, which are bothproducts of Brainlab AG.

US 2018/0078313 A1 discloses using multiple modalities of imaging forliver modelling from medical scan data. For liver modeling from medicalscan data, multiple modalities of imaging are used. By using multiplemodalities of imaging in combination with generative modeling, a morecomprehensive and informed assessment may be performed. The generativemodeling may allow feedback of effects of proposed therapy on functionof the liver. This feedback is used to update the liver functioninformation based on the imaging. Based on the computerized modelingwith information from various imaging modes, an output based on morecomprehensive information and patient personalized modeling and feedbackmay be provided to assist the physician.

US 2016/0005169 A1 discloses a method for producing an evolvable tissuemodel of a patient and, using this model, modelling physicaltransformations (e.g. deformation) of the tissue model by interactingthe tissue model with influence models which model interactions with thetissue such as surgical instruments, pressure, swelling, temperaturechanges etc. The model is produced from a set of input data of thetissue which includes directional information of the tissue. Thedirectional information is used to produce an oriented tissue map. Atissue model is then produced from the oriented tissue map such that thetissue model reflects the directionality of the tissue component. Whenthe tissue model is subjected to an influence that causes tissuedeformation over a period of time, the tissue model directionallydeforms over the period of time in a manner which reflects a trajectoryof the influence interacting with the directionality of the tissuecomponent.

Aspects of the present invention, examples and exemplary steps and theirembodiments are disclosed in the following. Different exemplary featuresof the invention can be combined in accordance with the inventionwherever technically expedient and feasible.

EXEMPLARY SHORT DESCRIPTION OF THE INVENTION

In the following, a short description of the specific features of thepresent invention is given which shall not be understood to limit theinvention only to the features or a combination of the featuresdescribed in this section.

The disclosed method encompasses determination of a currently executedstep of a workflow such as a medical intervention, the result of thedetermination serving as a basis for adapting and/or updating abiomechanical model of an anatomical body part to the correspondingcurrent status of the patient. The determination of the current workflowstep may also be used as basis for controlling an imaging device fortracking entities around the patient or for imaging the anatomical bodypart or acquiring further data or for urging the user to perform aspecific action such as acquisition of information using a trackedinstrument such as a pointer. The biomechanical model has been generatedfrom atlas data. The data sets which are generated according to thecurrent workflow step may additionally or alternatively serve as a basisfor determining the current workflow step and/or adapting the furtherworkflow.

GENERAL DESCRIPTION OF THE INVENTION

In this section, a description of the general features of the presentinvention is given for example by referring to possible embodiments ofthe invention.

In general, the invention reaches the aforementioned object byproviding, in a first aspect, a computer-implemented medical method ofadapting a biomechanical model of an anatomical body part of a patientto a current status of the patient. The method comprises executing, onat least one processor of at least one computer (for example at leastone computer being part of a navigation system), the following exemplarysteps which are executed by the at least one processor.

In a (for example first) exemplary step, initial biomechanical modeldata is acquired which describes an initial biomechanical model of theanatomical body part. For example, the biomechanical model is a finiteelement model or a coupled spring model of the anatomical body part. Forexample, the initial biomechanical model data has been generated basedon an atlas-based segmentation of patient image data describing adigital medical image of the anatomical body part, i.e. by establishinga mapping between atlas data describing an image-based model of theanatomical body part and patient image data describing a digital medicalimage of the anatomical body part for segmenting the imagerepresentation of the anatomical body part. For example, the anatomicalbody part comprises at least a part of the brain or at least a part ofthe liver.

In a (for example second) exemplary step, workflow step data is acquiredwhich describes a current step of a workflow of a procedure to becarried out on the patient. For example, tracking data is acquired whichdescribes a position of a medical entity, namely at least one of apatient, medical personnel or an instrument, and workflow stepdefinition data is acquired which describes an association between atleast one position of a medical entity, namely at least one of apatient, medical personnel or an instrument, and at least one step ofthe workflow of the procedure to be carried out on the patient: Forexample, the workflow step data is then acquired based on the trackingdata and the workflow step definition by comparing the positiondescribed by the tracking data to the workflow step definition data andby selecting the at least one step of the workflow being associated witha position of the medical entity corresponding to the position of themedical entity described by the tracking data as the current step of theworkflow. For example, the tracking data is generated by imaging, forexample video imaging, of at least one medical entity, for example atleast one of the patient, the anatomical body part, medical personnel ora medical instrument. According to another example, the tracking data isgenerated by optically or electromagnetically tracking at least onemarker device attached to at least one medical entity, for example atleast one of the patient, the anatomical body part, medical personnel ora medical instrument.

In a (for example third) exemplary step, status change data isdetermined based on the workflow step data and the initial biomechanicalmodel data, wherein the status change data describes a change in thepatient's status. For example, the change in the patient's status is achange in at least one of a position or the geometry of the patient'body, for example of the anatomical body part, or a relative positionbetween a medical instrument and the patient's body or a relativeposition between medical personnel and the patient's body, a timebetween changes of at least one of the aforementioned positions, aconfiguration or use of a medical instrument, a time interval duringwhich a medical instrument attains a specific position or a timeinterval which has expired starting from a predetermined point in timeduring the procedure.

In a (for example fourth) exemplary step, model adaptation data isacquired which describes an association between the change in thepatient's status and an adaptation to be applied to the initialbiomechanical model. The adaptation is defined as for example a changein the boundary conditions of the finite element model or coupled springmodel, respectively, for example by moving nodes, changing or adding orremoving mass points, or changing or adding or removing forces.

In (for example fifth) exemplary step, adapted biomechanical model datais determined based on the initial biomechanical model data and thestatus change data and the model adaptation data, wherein the adaptedbiomechanical model data describes an adapted biomechanical model whichis determined by applying the adaptation to the initial biomechanicalmodel. For example, the adapted biomechanical model data is determinedby changing the boundary conditions of the finite element model orcoupled spring model, respectively, for example by adding or removing ormoving nodes, changing or adding or removing mass points, or changing oradding or removing a force.

In an example of the method according to the first aspect,region-of-interest data is acquired based on the status change data,wherein the region-of-interest describes a region or trajectory, forexample an anatomical region or an object surface, in or on which aprocedure, for example the aforementioned procedure, is to be carriedout. For example, the method according to the first aspect comprisesacquiring, based on the region-of-interest-data, instrument positiondata which describes the position of a navigated instrument. Thenavigated instrument for example is a pointing device for identifyingposition, for example positions on the anatomical body part, for examplea pointer (such as a contactless pointer, for example a laser pointer,or pointer for identifying a position by placing its tip on theposition). For example, the instrument position data serves as anadditional basis for determining the adapted biomechanical model data.The navigated instrument is therefore usable as an input device forinputting positional information to a position tracking system used totrack the position of the navigated instrument and identify positions onthe anatomical body part. For example, a position on the anatomical bodypart can be identified by determining the position of the pointingdevice when it points at the anatomical body part. For example, at leastone position described by the instrument position data is used to changethe boundary conditions of the finite element model or coupled springmodel, for example to identify or add or remove a node of the initialbiomechanical model, a movement of such a node, to change or add orremove mass points, or to change or add or remove a force. Alternativelyor additionally, the procedure comprises acquiring, based on theregion-of interest data, video or medical image data describing at leasta part of the patient, for example the anatomical body part. Forexample, the procedure comprises acquiring the medical image data andthe imaging device used for generating the medical image data ishandheld or hand-guided or head-mounted or automatically guided, forexample by a robotic arm. In further examples, the imaging device is ahandheld or hand-guided or head-mounted or stationary ultrasound probeor a handheld or hand-guided or head-mounted or stationary infraredcamera or a three-dimensional image-generating scanner such as a scannerfor computed x-ray tomography or magnetic resonance tomography. Forexample, the medical image data serves as a basis for determining theadapted biomechanical data, e.g. by using the image informationcontained in the medical image data to change the boundary conditions ofthe finite element model or coupled spring model, for example toidentify or add or remove a node of the initial biomechanical model, amovement of such a node, to change or add or remove mass points, or tochange or add or remove a force.

In an example of the method according to the first aspect, imagingcontrol data is determined based on the status change data. The imagingcontrol data describes a command to be issued to the medical imagingdevice for taking an image of at least part of the anatomical body part.For example, the part of the anatomical body part to be imaged dependson the type of change of the patient's status. For example, the part ofthe anatomical body part to be imaged corresponds anatomically to thepart of the biomechanical model which is adapted for determining theadapted biomechanical model data. For example, the imaging control datais transmitted to the medical imaging device and executed, so thatmedical image data is determined which describes a medical image of thepart of the anatomical body part to be imaged.

In an example of the method according to the first aspect, instrumentguidance data is determined based on the status change data. Theinstrument guidance data describes a position at which an instrument isto be positioned. For example, the instrument is a navigated instrument,for example a pointing device such as a pointer. Thereby, a user or arobotic device for moving such an instrument can be provided withinformation (for example, visual guidance information for guiding theuser or control information for controlling the robotic device) where toposition the instrument for example for changing the boundary conditionsof the finite element model or coupled spring model, for exampleidentifying or adding or removing a node of the initial biomechanicalmodel, a movement of such a node, for changing or adding or removingmass points, or for changing or adding or removing a force.

In an example of the method according to the first aspect, imagingdevice guidance data is determined based on the status change data,wherein the imaging device guidance data describes a position at whichthe medical imaging device is to be positioned, for example so as to beable to take an image of the anatomical body part. Thereby, a user or arobotic device for moving the imaging device can be provided withinformation (for example, visual guidance information for guiding theuser or control information for controlling the robotic device) where toposition the imaging device.

In a second aspect, the invention is directed to a computer programcomprising instructions which, when the program is executed by at leastone computer, causes the at least one computer to carry out methodaccording to the first aspect. The invention may alternatively oradditionally relate to a (physical, for example electrical, for exampletechnically generated) signal wave, for example a digital signal wave,such as an electromagnetic carrier wave carrying information whichrepresents the program, for example the aforementioned program, whichfor example comprises code means which are adapted to perform any or allof the steps of the method according to the first aspect. The signalwave is in one example a data carrier signal carrying the aforementionedcomputer program. A computer program stored on a disc is a data file,and when the file is read out and transmitted it becomes a data streamfor example in the form of a (physical, for example electrical, forexample technically generated) signal. The signal can be implemented asthe signal wave, for example as the electromagnetic carrier wave whichis described herein. For example, the signal, for example the signalwave is constituted to be transmitted via a computer network, forexample LAN, WLAN, WAN, mobile network, for example the internet. Forexample, the signal, for example the signal wave, is constituted to betransmitted by optic or acoustic data transmission. The inventionaccording to the second aspect therefore may alternatively oradditionally relate to a data stream representative of theaforementioned program, i.e. comprising the program.

In a third aspect, the invention is directed to a computer-readablestorage medium on which the program according to the second aspect isstored. The program storage medium is for example non-transitory.

In a fourth aspect, the invention is directed to at least one computer(for example, a computer), comprising at least one processor (forexample, a processor), wherein the program according to the secondaspect is executed by the processor, or wherein the at least onecomputer comprises the computer-readable storage medium according to thethird aspect.

In a fifth aspect, the invention is directed to a medical system,comprising:

-   -   a) the at least one computer according to the fourth aspect;    -   b) at least one electronic data storage device storing at least        the initial biomechanical model data and the model adaptation        data; and    -   c) a medical device for carrying out a medical procedure on the        patient.

The at least one computer is operably coupled to the at least oneelectronic data storage device for acquiring, from the at least one datastorage device, at least the initial biomechanical model data and themodel adaptation data, and for storing, in the at least one data storagedevice, the adapted biomechanical model data.

In a sixth aspect, the invention is directed to the use of the systemaccording to the preceding claim for conducting a medical procedure,wherein the use comprises execution of the steps of the method accordingto any one of the preceding method claims for adapting a biomechanicalmodel of an anatomical body part of a patient to a current status of thepatient.

For example, the invention does not involve or in particular comprise orencompass an invasive step which would represent a substantial physicalinterference with the body requiring professional medical expertise tobe carried out and entailing a substantial health risk even when carriedout with the required professional care and expertise.

DEFINITIONS

In this section, definitions for specific terminology used in thisdisclosure are offered which also form part of the present disclosure.

The method in accordance with the invention is for example a computerimplemented method. For example, all the steps or merely some of thesteps (i.e. less than the total number of steps) of the method inaccordance with the invention can be executed by a computer (forexample, at least one computer). An embodiment of the computerimplemented method is a use of the computer for performing a dataprocessing method. An embodiment of the computer implemented method is amethod concerning the operation of the computer such that the computeris operated to perform one, more or all steps of the method.

The computer for example comprises at least one processor and forexample at least one memory in order to (technically) process the data,for example electronically and/or optically. The processor being forexample made of a substance or composition which is a semiconductor, forexample at least partly n- and/or p-doped semiconductor, for example atleast one of II-, III-, IV-, V-, VI-semiconductor material, for example(doped) silicon and/or gallium arsenide. The calculating or determiningsteps described are for example performed by a computer. Determiningsteps or calculating steps are for example steps of determining datawithin the framework of the technical method, for example within theframework of a program. A computer is for example any kind of dataprocessing device, for example electronic data processing device. Acomputer can be a device which is generally thought of as such, forexample desktop PCs, notebooks, netbooks, etc., but can also be anyprogrammable apparatus, such as for example a mobile phone or anembedded processor. A computer can for example comprise a system(network) of “sub-computers”, wherein each sub-computer represents acomputer in its own right. The term “computer” includes a cloudcomputer, for example a cloud server. The term computer includes aserver resource. The term “cloud computer” includes a cloud computersystem which for example comprises a system of at least one cloudcomputer and for example a plurality of operatively interconnected cloudcomputers such as a server farm. Such a cloud computer is preferablyconnected to a wide area network such as the world wide web (WWW) andlocated in a so-called cloud of computers which are all connected to theworld wide web. Such an infrastructure is used for “cloud computing”,which describes computation, software, data access and storage serviceswhich do not require the end user to know the physical location and/orconfiguration of the computer delivering a specific service. Forexample, the term “cloud” is used in this respect as a metaphor for theInternet (world wide web). For example, the cloud provides computinginfrastructure as a service (IaaS). The cloud computer can function as avirtual host for an operating system and/or data processing applicationwhich is used to execute the method of the invention. The cloud computeris for example an elastic compute cloud (EC2) as provided by Amazon WebServices™. A computer for example comprises interfaces in order toreceive or output data and/or perform an analogue-to-digital conversion.The data are for example data which represent physical properties and/orwhich are generated from technical signals. The technical signals arefor example generated by means of (technical) detection devices (such asfor example devices for detecting marker devices) and/or (technical)analytical devices (such as for example devices for performing (medical)imaging methods), wherein the technical signals are for exampleelectrical or optical signals. The technical signals for examplerepresent the data received or outputted by the computer. The computeris preferably operatively coupled to a display device which allowsinformation outputted by the computer to be displayed, for example to auser. One example of a display device is a virtual reality device or anaugmented reality device (also referred to as virtual reality glasses oraugmented reality glasses) which can be used as “goggles” fornavigating. A specific example of such augmented reality glasses isGoogle Glass (a trademark of Google, Inc.). An augmented reality deviceor a virtual reality device can be used both to input information intothe computer by user interaction and to display information outputted bythe computer. Another example of a display device would be a standardcomputer monitor comprising for example a liquid crystal displayoperatively coupled to the computer for receiving display control datafrom the computer for generating signals used to display imageinformation content on the display device. A specific embodiment of sucha computer monitor is a digital lightbox. An example of such a digitallightbox is Buzz®, a product of Brainlab AG. The monitor may also be themonitor of a portable, for example handheld, device such as a smartphone or personal digital assistant or digital media player.

The invention also relates to a computer program comprising instructionswhich, when on the program is executed by a computer, cause the computerto carry out the method or methods, for example, the steps of the methodor methods, described herein and/or to a computer-readable storagemedium (for example, a non-transitory computer-readable storage medium)on which the program is stored and/or to a computer comprising saidprogram storage medium and/or to a (physical, for example electrical,for example technically generated) signal wave, for example a digitalsignal wave, such as an electromagnetic carrier wave carryinginformation which represents the program, for example the aforementionedprogram, which for example comprises code means which are adapted toperform any or all of the method steps described herein. The signal waveis in one example a data carrier signal carrying the aforementionedcomputer program. The invention also relates to a computer comprising atleast one processor and/or the aforementioned computer-readable storagemedium and for example a memory, wherein the program is executed by theprocessor.

Within the framework of the invention, computer program elements can beembodied by hardware and/or software (this includes firmware, residentsoftware, micro-code, etc.). Within the framework of the invention,computer program elements can take the form of a computer programproduct which can be embodied by a computer-usable, for examplecomputer-readable data storage medium comprising computer-usable, forexample computer-readable program instructions, “code” or a “computerprogram” embodied in said data storage medium for use on or inconnection with the instruction-executing system. Such a system can be acomputer; a computer can be a data processing device comprising meansfor executing the computer program elements and/or the program inaccordance with the invention, for example a data processing devicecomprising a digital processor (central processing unit or CPU) whichexecutes the computer program elements, and optionally a volatile memory(for example a random access memory or RAM) for storing data used forand/or produced by executing the computer program elements. Within theframework of the present invention, a computer-usable, for examplecomputer-readable data storage medium can be any data storage mediumwhich can include, store, communicate, propagate or transport theprogram for use on or in connection with the instruction-executingsystem, apparatus or device. The computer-usable, for examplecomputer-readable data storage medium can for example be, but is notlimited to, an electronic, magnetic, optical, electromagnetic, infraredor semiconductor system, apparatus or device or a medium of propagationsuch as for example the Internet. The computer-usable orcomputer-readable data storage medium could even for example be paper oranother suitable medium onto which the program is printed, since theprogram could be electronically captured, for example by opticallyscanning the paper or other suitable medium, and then compiled,interpreted or otherwise processed in a suitable manner. The datastorage medium is preferably a non-volatile data storage medium. Thecomputer program product and any software and/or hardware described hereform the various means for performing the functions of the invention inthe example embodiments. The computer and/or data processing device canfor example include a guidance information device which includes meansfor outputting guidance information. The guidance information can beoutputted, for example to a user, visually by a visual indicating means(for example, a monitor and/or a lamp) and/or acoustically by anacoustic indicating means (for example, a loudspeaker and/or a digitalspeech output device) and/or tactilely by a tactile indicating means(for example, a vibrating element or a vibration element incorporatedinto an instrument). For the purpose of this document, a computer is atechnical computer which for example comprises technical, for exampletangible components, for example mechanical and/or electroniccomponents. Any device mentioned as such in this document is a technicaland for example tangible device.

The expression “acquiring data” for example encompasses (within theframework of a computer implemented method) the scenario in which thedata are determined by the computer implemented method or program.Determining data for example encompasses measuring physical quantitiesand transforming the measured values into data, for example digitaldata, and/or computing (and e.g. outputting) the data by means of acomputer and for example within the framework of the method inaccordance with the invention. A step of “determining” as describedherein for example comprises or consists of issuing a command to performthe determination described herein. For example, the step comprises orconsists of issuing a command to cause a computer, for example a remotecomputer, for example a remote server, for example in the cloud, toperform the determination. Alternatively or additionally, a step of“determination” as described herein for example comprises or consists ofreceiving the data resulting from the determination described herein,for example receiving the resulting data from the remote computer, forexample from that remote computer which has been caused to perform thedetermination. The meaning of “acquiring data” also for exampleencompasses the scenario in which the data are received or retrieved by(e.g. input to) the computer implemented method or program, for examplefrom another program, a previous method step or a data storage medium,for example for further processing by the computer implemented method orprogram. Generation of the data to be acquired may but need not be partof the method in accordance with the invention. The expression“acquiring data” can therefore also for example mean waiting to receivedata and/or receiving the data. The received data can for example beinputted via an interface. The expression “acquiring data” can also meanthat the computer implemented method or program performs steps in orderto (actively) receive or retrieve the data from a data source, forinstance a data storage medium (such as for example a ROM, RAM,database, hard drive, etc.), or via the interface (for instance, fromanother computer or a network). The data acquired by the disclosedmethod or device, respectively, may be acquired from a database locatedin a data storage device which is operably to a computer for datatransfer between the database and the computer, for example from thedatabase to the computer. The computer acquires the data for use as aninput for steps of determining data. The determined data can be outputagain to the same or another database to be stored for later use. Thedatabase or database used for implementing the disclosed method can belocated on network data storage device or a network server (for example,a cloud data storage device or a cloud server) or a local data storagedevice (such as a mass storage device operably connected to at least onecomputer executing the disclosed method). The data can be made “readyfor use” by performing an additional step before the acquiring step. Inaccordance with this additional step, the data are generated in order tobe acquired. The data are for example detected or captured (for exampleby an analytical device). Alternatively or additionally, the data areinputted in accordance with the additional step, for instance viainterfaces. The data generated can for example be inputted (for instanceinto the computer). In accordance with the additional step (whichprecedes the acquiring step), the data can also be provided byperforming the additional step of storing the data in a data storagemedium (such as for example a ROM, RAM, CD and/or hard drive), such thatthey are ready for use within the framework of the method or program inaccordance with the invention. The step of “acquiring data” cantherefore also involve commanding a device to obtain and/or provide thedata to be acquired. In particular, the acquiring step does not involvean invasive step which would represent a substantial physicalinterference with the body, requiring professional medical expertise tobe carried out and entailing a substantial health risk even when carriedout with the required professional care and expertise. In particular,the step of acquiring data, for example determining data, does notinvolve a surgical step and in particular does not involve a step oftreating a human or animal body using surgery or therapy. In order todistinguish the different data used by the present method, the data aredenoted (i.e. referred to) as “XY data” and the like and are defined interms of the information which they describe, which is then preferablyreferred to as “XY information” and the like.

Preferably, atlas data is acquired which describes (for example defines,more particularly represents and/or is) a general three-dimensionalshape of the anatomical body part. The atlas data therefore representsan atlas of the anatomical body part. An atlas typically consists of aplurality of generic models of objects, wherein the generic models ofthe objects together form a complex structure. For example, the atlasconstitutes a statistical model of a patient's body (for example, a partof the body) which has been generated from anatomic information gatheredfrom a plurality of human bodies, for example from medical image datacontaining images of such human bodies. In principle, the atlas datatherefore represents the result of a statistical analysis of suchmedical image data for a plurality of human bodies. This result can beoutput as an image—the atlas data therefore contains or is comparable tomedical image data. Such a comparison can be carried out for example byapplying an image fusion algorithm which conducts an image fusionbetween the atlas data and the medical image data. The result of thecomparison can be a measure of similarity between the atlas data and themedical image data. The atlas data comprises image information (forexample, positional image information) which can be matched (for exampleby applying an elastic or rigid image fusion algorithm) for example toimage information (for example, positional image information) containedin medical image data so as to for example compare the atlas data to themedical image data in order to determine the position of anatomicalstructures in the medical image data which correspond to anatomicalstructures defined by the atlas data.

The human bodies, the anatomy of which serves as an input for generatingthe atlas data, advantageously share a common feature such as at leastone of gender, age, ethnicity, body measurements (e.g. size and/or mass)and pathologic state. The anatomic information describes for example theanatomy of the human bodies and is extracted for example from medicalimage information about the human bodies. The atlas of a femur, forexample, can comprise the head, the neck, the body, the greatertrochanter, the lesser trochanter and the lower extremity as objectswhich together make up the complete structure. The atlas of a brain, forexample, can comprise the telencephalon, the cerebellum, thediencephalon, the pons, the mesencephalon and the medulla as the objectswhich together make up the complex structure. One application of such anatlas is in the segmentation of medical images, in which the atlas ismatched to medical image data, and the image data are compared with thematched atlas in order to assign a point (a pixel or voxel) of the imagedata to an object of the matched atlas, thereby segmenting the imagedata into objects.

For example, the atlas data includes information of the anatomical bodypart. This information is for example at least one of patient-specific,non-patient-specific, indication-specific or non-indication-specific.The atlas data therefore describes for example at least one of apatient-specific, non-patient-specific, indication-specific ornon-indication-specific atlas. For example, the atlas data includesmovement information indicating a degree of freedom of movement of theanatomical body part with respect to a given reference (e.g. anotheranatomical body part). For example, the atlas is a multimodal atlaswhich defines atlas information for a plurality of (i.e. at least two)imaging modalities and contains a mapping between the atlas informationin different imaging modalities (for example, a mapping between all ofthe modalities) so that the atlas can be used for transforming medicalimage information from its image depiction in a first imaging modalityinto its image depiction in a second imaging modality which is differentfrom the first imaging modality or to compare (for example, match orregister) images of different imaging modality with one another.

In the field of medicine, imaging methods (also called imagingmodalities and/or medical imaging modalities) are used to generate imagedata (for example, two-dimensional or three-dimensional image data) ofanatomical structures (such as soft tissues, bones, organs, etc.) of thehuman body. The term “medical imaging methods” is understood to mean(advantageously apparatus-based) imaging methods (for example so-calledmedical imaging modalities and/or radiological imaging methods) such asfor instance computed tomography (CT) and cone beam computed tomography(CBCT, such as volumetric CBCT), x-ray tomography, magnetic resonancetomography (MRT or MRI), conventional x-ray, sonography and/orultrasound examinations, and positron emission tomography. For example,the medical imaging methods are performed by the analytical devices.Examples for medical imaging modalities applied by medical imagingmethods are: X-ray, magnetic resonance imaging, medical ultrasonographyor ultrasound, endoscopy, elastography, tactile imaging, thermography,medical photography and nuclear medicine functional imaging techniquesas positron emission tomography (PET) and Single-photon emissioncomputed tomography (SPECT). The image data thus generated is alsotermed “medical imaging data”. Analytical devices for example are usedto generate the image data in apparatus-based imaging methods. Theimaging methods are for example used for medical diagnostics, to analysethe anatomical body in order to generate images which are described bythe image data. The imaging methods are also for example used to detectpathological changes in the human body. However, some of the changes inthe anatomical structure, such as the pathological changes in thestructures (tissue), may not be detectable and for example may not bevisible in the images generated by the imaging methods. A tumourrepresents an example of a change in an anatomical structure. If thetumour grows, it may then be said to represent an expanded anatomicalstructure. This expanded anatomical structure may not be detectable; forexample, only a part of the expanded anatomical structure may bedetectable. Primary/high-grade brain tumours are for example usuallyvisible on MRI scans when contrast agents are used to infiltrate thetumour. MRI scans represent an example of an imaging method. In the caseof MRI scans of such brain tumours, the signal enhancement in the MRIimages (due to the contrast agents infiltrating the tumour) isconsidered to represent the solid tumour mass. Thus, the tumour isdetectable and for example discernible in the image generated by theimaging method. In addition to these tumours, referred to as “enhancing”tumours, it is thought that approximately 10% of brain tumours are notdiscernible on a scan and are for example not visible to a user lookingat the images generated by the imaging method.

Mapping describes a transformation (for example, linear transformation)of an element (for example, a pixel or voxel), for example the positionof an element, of a first data set in a first coordinate system to anelement (for example, a pixel or voxel), for example the position of anelement, of a second data set in a second coordinate system (which mayhave a basis which is different from the basis of the first coordinatesystem). In one embodiment, the mapping is determined by comparing (forexample, matching) the color values (for example grey values) of therespective elements by means of an elastic or rigid fusion algorithm.The mapping is embodied for example by a transformation matrix (such asa matrix defining an affine transformation).

A pointer is for example a rod which comprises one ormore—advantageously, two—markers fastened to it and which can be used tomeasure off individual co-ordinates, for example spatial co-ordinates(i.e. three-dimensional co-ordinates), on a part of the body, wherein auser guides the pointer (for example, a part of the pointer which has adefined and advantageously fixed position with respect to the at leastone marker attached to the pointer) to the position corresponding to theco-ordinates, such that the position of the pointer can be determined byusing a navigation system (also called position tracking system) to forexample optically or electromagnetically detect the marker on thepointer. The relative location between the markers of the pointer andthe part of the pointer used to measure off co-ordinates (for example,the tip of the pointer) is for example known. The surgical navigationsystem then enables the location (of the three-dimensional co-ordinates)to be assigned to a predetermined body structure, wherein the assignmentcan be made automatically or by user intervention. A pointer is inanother example a light pointer (for example laser pointer) whichidentifies a position by i.a. irradiating it with a narrow light beam.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described with reference to theappended figures which give background explanations and representspecific embodiments of the invention. The scope of the invention ishowever not limited to the specific features disclosed in the context ofthe figures, wherein

FIG. 1 illustrates a basic flow of the method according to the firstaspect;

FIG. 2 shows an application of the method according to the first aspect;and

FIG. 3 is a schematic illustration of the system according to the fifthaspect.

DESCRIPTION OF EMBODIMENTS

FIG. 1 illustrates the basic steps of the method according to the firstaspect, in which step S1 encompasses acquisition of the initialbiomechanical model data, step S2 encompasses acquisition of theworkflow step data and subsequent step S3 encompasses determination ofthe status change data. The method then continues with acquiring themodel adaptation data in step S4 and determining the adaptedbiomechanical model data in step S5.

FIG. 2 describes an application of the method according to the firstaspect. Workflow data 4 is acquired and a current workflow data isdetermined so as to correspondingly adapt the biomechanical model 10.The workflow data 4 may also be used as a basis for triggering 7 theinput of other intraprocedural data 8 or for using 9 the otherintraprocedural data 8 for adapting the biomechanical model 10 which hasinitially been generated by generating 11 a model from atlas data 12.The adapted biomechanical model 10 may also be used for feedback intothe workflow so as to determine the current workflow step from theadapted biomechanical model 10 e.g. if the workflow step data isreplaced by up-to-date image data as basis for adapting thebiomechanical model 10. The current workflow step may be determined 6from image data taken as video data 1 or with a tracked imaging device 2such as a microscope or from intraprocedural data 8. The image data mayalso be used to directly adapt the biomechanical model 10. The currentworkflow step may also be used to initiate imaging e.g. with a tomograph5, wherein the generated image may be used as a basis for adapting thebiomechanical model 10. Also, the current workflow step may be used as abasis for initiating acquisition of positional data with a trackedinstrument 3. The image data generated with the tomograph 5 may also beused to determine the current workflow step. The current workflow stepmay also be used to initiate operation of a video camera for generatingthe image data 1 or the tracked imaging device 2. Use of the trackedpointer 3 may also be used as a basis for determining the currentworkflow step.

FIG. 3 is a schematic illustration of the medical system 13 according tothe fifth aspect. The system is in its entirety identified by referencesign 13 and comprises a computer 14, and an electronic data storagedevice (such as a hard disc) 15 for storing at least the patient data.The components of the medical system 13 have the functionalities andproperties explained above with regard to the fifth aspect of thisdisclosure.

The following exemplary aspects are also part of possible embodiments ofthe invention.

-   -   The initial biomechanical model data is generated based on        physical, e.g. mechanical, properties of the tissue types, e.g.        tissue classes, stored in the atlas.    -   The workflow step data can be generated based on intraoperative        image data, e.g. from an x-ray device, fluoroscopy device, x-ray        tomograph, magnetic resonance tomograph, C-arm, on        intraoperative video data, e.g. from an endoscope or microscope        or exoscope or external camera with a field of view to the        surgical site, on ultrasound image data, on the position, speed        and acceleration of instruments or imaging devices, e.g. as a        function of time. The workflow step data can be based on        contents of the intraoperative video data, such as a position or        speed or acceleration of an instrument or implant or an        anatomical object in an image, e.g. as a function of time.    -   The workflow step data can also be based on other intraoperative        or intraprocedural data, such as the status of a device in the        operating room, e.g. “switched on” or “switched off”, the device        can be for example an anaesthesia device. Physiological data of        the patient.    -   The workflow step data can be determined by comparing the        intraoperative data to predetermined criteria, such as a        predetermined pattern for the other intraoperative image data,        video data or other intraoperative data using a predetermined        relation between the pattern and a workflow step.    -   The workflow step data can also be determined using a learning        algorithm: In a learning phase, the events are labelled manually        and input into a learning algorithm together with the        intraoperative data. The learning algorithm is e.g. based on a        Convolutional Neural Network or Recurrent Neural Network. During        the using phase of the learning algorithm, which takes place        after the learning phase, the intraoperative data are input and        the event is output by the learning algorithm based on the        learning data acquired during the learning phase.    -   The workflow step data can also be based on a stored workflow        for the type of procedure performed. Such a stored workflow        consists of a number of predetermined steps.    -   The current step of the workflow is e.g. opening of the dura,        the performing of a resection, performing a craniotomy,        installation of a drainage, setup of the patient, use of a        suction device, suction of cerebrospinal fluid, tissue removal,        application of pharmaceuticals.    -   The status change data comprises e.g. that the dura was opened,        that a resection was performed, that instruments are in place.    -   A handheld or hand-guided or automatically guided imaging device        is e.g. an ultrasound probe, a microscope or an endoscope.    -   To support image acquisition with a handheld device, the ROI can        be indicated to a user on a display, e.g. an augmented reality        display.

1. A computer-implemented method comprising: acquiring initialbiomechanical model data which describes an initial biomechanical modelof the anatomical body part; acquiring workflow step data whichdescribes a current step of a workflow of a procedure to be carried outon the patient; determining status change data based on the workflowstep data and the initial biomechanical model data, wherein the statuschange data describes a change in the patient's status; acquiring modeladaptation data which describes an association between the change in thepatient's status and an adaptation to be applied to the initialbiomechanical model; determining adapted biomechanical model data basedon the initial biomechanical model data and the status change data andthe model adaptation data, wherein the adapted biomechanical model datadescribes an adapted biomechanical model which is determined by applyingthe adaptation to the initial biomechanical model.
 2. The methodaccording to claim 1, further comprising acquiring region-of-interestdata based on the status change data, wherein the region-of-interestdescribes an anatomical region.
 3. The method according to claim 1,further comprising acquiring, based on the region-of-interest-data,instrument position data which describes the position of a navigatedinstrument and/or acquiring, based on the region-of interest data,medical image data describing at least an anatomical body part of thepatient.
 4. The method according to claim 1, comprising: acquiring themedical image data, wherein the imaging device used for generating themedical image data is handheld or hand-guided or head-mounted orautomatically guided.
 5. The method according to claim 3, comprising:acquiring the instrument position data, wherein the adaptedbiomechanical model data is determined based on the instrument positiondata and/or acquiring the medical image data, wherein the adaptedbiomechanical model data is determined based on the medical image data.6. The method according to claim 1, further comprising determiningimaging control data based on the status change data, wherein theimaging control data describes a command to be issued to a medicalimaging device for taking an image of at least part of the anatomicalbody part.
 7. The method according to claim 6, wherein the part of theanatomical body part to be imaged depends on the type of change of thepatient's status.
 8. The method according to claim 7, wherein the partof the anatomical body part to be imaged corresponds anatomically to thepart of the biomechanical model which is adapted for determining theadapted biomechanical model data.
 9. The method according to claim 8,wherein the imaging control data is transmitted to the medical imagingdevice and executed, so that medical image data is determined whichdescribes a medical image of the part of the anatomical body part to beimaged.
 10. The method according to claim 1, further comprisingdetermining instrument guidance data is determined based on the statuschange data, wherein the instrument guidance data describes a positionat which an instrument is to be positioned.
 11. The method according toclaim 10, wherein the instrument is a navigated instrument.
 12. Themethod according to claim 1, further comprising determining imagingdevice guidance data based on the status change data, wherein theimaging device guidance data describes a position at which a medicalimaging device is to be positioned.
 13. The method according to claim 1,wherein the biomechanical model is a finite element model or a coupledspring model of the anatomical body part, and wherein the adaptedbiomechanical model data is determined by changing the boundaryconditions of the finite element model or coupled spring model,respectively.
 14. The method according to claim 1, wherein the initialbiomechanical model data has been generated based on an atlas-basedsegmentation of patient image data describing a digital medical image ofthe anatomical body part.
 15. The method according to claim 1, whereinthe anatomical body part comprises at least a part of the brain or atleast a part of the liver.
 16. The method according to claim 1, whereinthe change in the patient's status is a change in at least one of aposition or the geometry of the patient' body, or a change in a relativeposition between a medical instrument and the patient's body or a changein a relative position between medical personnel and the patient's body,a time between changes of at least one of the aforementioned positions,a configuration or use of a medical instrument, a time interval duringwhich a medical instrument attains a specific position or a timeinterval which has expired starting from a predetermined point in timeduring the procedure.
 17. The method according to claim 1, furthercomprising acquiring tracking data which describes a position of amedical entity, namely at least one of a patient, medical personnel oran instrument; acquiring workflow step definition data which describesan association between at least one position of a medical entity, and atleast one step of the workflow of the procedure to be carried out on thepatient; the workflow step data is acquired based on the tracking dataand the workflow step definition by comparing the position described bythe tracking data to the workflow step definition data and by selectingthe at least one step of the workflow being associated with a positionof the medical entity corresponding to the position of the medicalentity described by the tracking data as the current step of theworkflow.
 18. The method according to claim 17, wherein the trackingdata is generated by imaging, of at least one medical entity.
 19. Themethod according to claim 18, wherein the tracking data is generated byoptically or electromagnetically tracking at least one marker deviceattached to at least one medical entity, for.
 20. A non-transitorycomputer readable storage medium storing computer instructions which,when executed by at least one processor, cause the at least oneprocessor to: acquire initial biomechanical model data which describesan initial biomechanical model of the anatomical body part; acquireworkflow step data which describes a current step of a workflow of aprocedure to be carried out on the patient; determine status change databased on the workflow step data and the initial biomechanical modeldata, wherein the status change data describes a change in the patient'sstatus; acquire model adaptation data which describes an associationbetween the change in the patient's status and an adaptation to beapplied to the initial biomechanical model; determine adaptedbiomechanical model data based on the initial biomechanical model dataand the status change data and the model adaptation data; wherein theadapted biomechanical model data describes an adapted biomechanicalmodel which is determined by applying the adaptation to the initialbiomechanical model. 21.-24. (canceled)
 25. A system, comprising: atleast one processor to execute instructions stored on memory causing theat least one processor to: acquire initial biomechanical model datawhich describes an initial biomechanical model of the anatomical bodypart; acquire workflow step data which describes a current step of aworkflow of a procedure to be carried out on the patient; determinestatus change data based on the workflow step data and the initialbiomechanical model data, wherein the status change data describes achange in the patient's status; acquire model adaptation data whichdescribes an association between the change in the patient's status andan adaptation to be applied to the initial biomechanical model;determine adapted biomechanical model data based on the initialbiomechanical model data and the status change data and the modeladaptation data; wherein the adapted biomechanical model data describesan adapted biomechanical model which is determined by applying theadaptation to the initial biomechanical model; at least one electronicdata storage device storing at least the initial biomechanical modeldata and the model adaptation data; and a medical device, wherein the atleast one processor is operably coupled to the at least one electronicdata storage device for acquiring, from the at least one data storagedevice, at least the initial biomechanical model data and the modeladaptation data, and for storing, in the at least one data storagedevice, the adapted biomechanical model data.
 26. (canceled)